C# · 12月 23, 2021

c# – 等待多个回调

我正在使用一个执行异步调用的库,当返回响应时,将调用带有结果的回调方法.这是一个简单的模式,但我现在遇到了障碍.如何对异步方法进行多次调用并等待(不阻塞)它们?当我从所有服务获得数据时,我想调用我自己的回调方法,该方法将获得异步方法返回的两个(或更多)值.

这里遵循的正确模式是什么?顺便说一句,我不能改变库使用TPL或其他东西……我必须忍受它.

public static void GetDataAsync(Action<int,int> callback){ Service.Instance.GetData(r1 => { Debug.Assert(r1.Success); }); Service.Instance.GetData2(r2 => { Debug.Assert(r2.Success); }); // How do I call the action “callback” without blocking when the two methods have finished to execute? // callback(r1.Data,r2.Data);}解决方法 你想要的是像 CountdownEvent.试试这个(假设你在.NET 4.0上): public static void GetDataAsync(Action<int,int> callback){ // Two here because we are going to wait for 2 events- adjust accordingly var latch = new CountdownEvent(2); Object r1Data,r2Data; Service.Instance.GetData(r1 => { Debug.Assert(r1.Success); r1Data = r1.Data; latch.Signal(); }); Service.Instance.GetData2(r2 => { Debug.Assert(r2.Success); r2Data = r2.Data; latch.Signal(); }); // How do I call the action “callback” without blocking when the two methods have finished to execute? // callback(r1.Data,r2.Data); ThreadPool.QueueUserWorkItem(() => { // This will execute on a threadpool thread,so the // original caller is not blocked while the other async’s run latch.Wait(); callback(r1Data,r2Data); // Do whatever here- the async’s have Now completed. });}